%0 Journal Article %A V. V. Lychagin %T On sufficient orbits of a~group of contact diffeomorphisms %J Sbornik. Mathematics %D 1977 %P 223-242 %V 33 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/SM_1977_33_2_a3/ %G en %F SM_1977_33_2_a3